Israeli forces hit the city of Jenin with drone strikes during an overnight operation on Monday that left at least seven people dead.
The Palestinian health ministry confirmed at least seven people had been killed and 27 wounded in Jenin, while another man was killed in the city of Ramallah after being shot in the head at a checkpoint.
As daylight broke on Monday, thick black smoke from burning tyres set alight by residents swirled through the Jenin streets while calls to support the fighters rang out from loudspeakers.
A spokesman for Palestinian President Mahmoud Abbas called the operation "a new war crime against our defenceless people".
The Israeli military said the targeted building functioned as an "advanced observation and reconnaissance centre" and a weapons and explosives site as well as a coordination and communications hub.
It provided an aerial photograph showing what it said was the target and which indicated the building hit was near two schools and a medical centre.
A spokesman said it would last as long as needed and officials suggested forces could remain for days. "An operation doesn't end in one day," Energy Minister Israel Katz, a member of the security cabinet, told Army radio.
Israeli Defence Minister Yoav Gallant said his forces were "closely monitoring the conduct of our enemies...The defence establishment is ready for all scenarios."
Israel and Iran attacked each other for a fifth straight day on Tuesday, and US President Donald Trump urged Iranians to evacuate Tehran, citing what he said was the country's rejection of a deal to curb nuclear weapons development.
Israeli tank shellfire killed at least 51 Palestinians on Tuesday as they awaited aid trucks in Khan Younis in the southern Gaza Strip, the territory's health ministry said, adding that dozens of others were wounded.
Russia launched hundreds of drones and dozens of missilesat Ukraine on Tuesday,hitting dozens of civilian targets in Kyiv including a large apartment block, killing at least 15 people and wounding scores, Ukrainian officials said.
US President Donald Trump left the Group of Seven summit in Canada a day early due to the situation in the Middle East, the White House said on Monday.
The U.S. military has moved a large number of refueling aircraft to Europe to provide options to President Donald Trump as Middle East tensions erupt into conflict between Iran and Israel, two U.S. officials told Reuters on Monday, speaking on condition of anonymity.